In the United States alone, over 1.5 million persons annually suffer from intractable ischemia or acute myocardial infarction, or both. It is known to use retroperfusion techniques to treat such conditions. Retroperfusion techniques for the heart generally involve the delivery of arterial oxygenated or venous blood. This blood is delivered retrogradedly to the endangered ischemic myocardium through its adjoining coronary veins in a direction opposite to the normal outflow of venous blood through that vein. That retroperfused blood crosses from the coronary veins into the tissue capillary circulation, e.g., as microcirculation, to provide blood and nourishment to an underperfused myocardium.
Coronary sinus retroperfusion limits or reduces myocardial damage when administered as a preemptive or remedial treatment, or both. Coronary sinus retroperfusion also may be effective therapy when targeted to slow or, in some cases, reverse the progression from myocardial ischemia to the irreversible damage associated with myocardial infarction. Further, coronary sinus retroperfusion may provide a temporary therapeutic window to achieve even more complete revascularization, such as by Percutaneous Transluminal Coronary Angioplasty (PTCA) or Coronary Artery By-Pass Grafting (CABG), and may also permit physicians to improve myocardial salvage.
Typically, a two-step surgical procedure is utilized that involves creating an interventional shunt from an artery to the coronary sinus (venous circulation), and subsequently restricting the blood flow through the coronary sinus, such as with an occluding balloon, to facilitate effective retroperfusion of coronary veins with arterial blood provided via an intraluminal catheter. The occlusion of the coronary sinus helps to prevent excessive back-flow of blood into the right atrium.
The balloon used to occlude the coronary sinus is often also used to retain the intraluminal catheter in place inside the patient. The balloon is inflated inside the ostium downstream of the middle cardiac vein (serving the right ventricular territory), in the space between the middle cardiac vein and the veins coming from the left ventricle. This infusion thus occurs distal to the balloon. Because the space upstream of the middle cardiac vein between the ostium and the middle cardiac vein is too small to contain the balloon, the middle cardiac vein must be excluded from the perfusion. Consequently, the right ventricle is left unprotected during heart surgery. Therefore, although vessel occlusion may be required in a retroperfusion procedure, use of the inflated balloon to occlude the vessel can be disadvantageous.
Attempts have been made to improve the catheter design to minimize the obstruction of the branch lumens. These catheter designs included shortening the retention balloons. Although the use of protuberances or ridges on the balloon surface to improve the frictional contact has been suggested, the shortened balloon may provide insufficient frictional contact with the lumen surface. Fixation balloons made of an open-walled element material, which permits blood to flow freely through the open-walled element material, are also known.